Confusion regarding declaration of small amounts of a psychotropic drug (alprazolam aka xanax)

I'm currently filling out the Visit Japan Web customs info stuff, and I'm a bit confused regarding the "Are you bringing the following into Japan? (1) Prohibited items(s) from being brought into Japan (e.g. Narcotic drugs, Firearms, and Explosives)" section.

I'm going to have a small prescription of alprazolam (xanax) with me, which is considered a psychotropic drug in Japan. The amount is going to be far under a month's supply, as it's primarily intended for the flight to/from Japan. Does this need to be declared when filling out the Visit Japan Web customs info?

My confusion is stemming from reading that any prescription doesn't need to be declared, as long as it's under a month's supply and doesn't contain amphetamines. However, the wording of the question says nothing about quantity.